Anyone running a compound setup on a L-series

[Tony D]

To This:

 

"Contrary to what people believe the small turbo does not become a restriction, it does become a pressure multiplier. With the increased inlet pressure, it flows more than it would if the inlet pressure were lower."

 

Please look up the definition of "Stonewall"---there IS a limit physically as to what diameter and blade spacing into what torridal diffuser (and flow path dimension) will ultimately flow. You will not put the flow of a T67 through a stock turbo housing without restricting the T67's flow.

 

This gets to the differences between 'flow' and 'pressure'.... You raise the inlet pressure and flow increases. But ULTIMATELY the presence of PRESSURE at the smaller turbo's inlet SIGNIFIES RESTRICTION TO FLOW!

 

Multistaging for flow is best done in pure parallel for simplicity. COMPOUNDING is not the way you want to do it in low pressure applications, it's just NOT efficient. There may be an argument for two stages between 45-75 psi, it's a strange range to be in, and they may derate two stage machines to operate there....but nobody is pumping 45psi into an L-Motor, that would be well into the 1500HP range.

 

Show me one high-flow industrial compressor below 50PSI design pressure that is two-stage.  They don't do it.  For 100psi there is an argument between 2 or three stages, and above 100psig to around 200-250 the argument is made over 3 or four stages, between 275-400 4 stages is standard, with 4 stages being a standard offering in most 350 psi applications. At 5 stages, 700psi is easily attainable. If there is an EFFICIENT way to do it, it will show up in Industrial Compressors well before automotive applications as the marketing and costs for driver power drive the market. 1 or 2% will make or break a sale.

 

In some cases, Japanese have a culture of making things technologically complex to it's own end. That's not really engineering, it's masturbation. if you can get it done with fewer parts....DO IT!

[TimZ]

I've compared my car with stock F54 and flattops (stock), pulled the engine, installed dished pistons, and went to the drag strip a week later with no other changes to the engine and found a substantial difference in spooling time between flattops and dished.

 

When staging on the brake to build boost with an automatic at the drag strip, you will immediately notice the difference.

 

Compression equals heat.

 

Yes, compressing a gas will increase it's temperature, but that's not what we are talking about here.  

 

Increasing the compression ratio will increase combustion efficiency, which by definition means that more of the energy from combustion goes into work at the crank and less goes out the exhaust.  All else equal, you will see lower EGTs with increased compression.

 

In your example there are several unstated and uncontrolled variables that could have caused the results you stated - was the ambient air pressure and temperature exactly the same on that run a week later?  Did you have to change ignition timing to stay below the knock limit with the increased CR?  Did you use different fuel to accommodate the increased CR?

 

You don't have to take my word for it - it's pretty well established thermodynamic rules. Here's a link to a paper from Stanford University that covers the subject nicely:  http://rescomp.stanford.edu/~efroeh/papers/RDH_Engine_Performance.pdf

Edited February 15, 2013 by TimZ

[Tony D]

Hahaha

 

"Education comes after Anecdote in every dictionary, damn the physical laws, regardless of how well documented! It just doesn't apply in my example!"

 

I have just summarised every response from here on.

[HowlerMonkey]

 

 

Yes, compressing a gas will increase it's temperature, but that's not what we are talking about here.  

 

Increasing the compression ratio will increase combustion efficiency, which by definition means that more of the energy from combustion goes into work at the crank and less goes out the exhaust.  All else equal, you will see lower EGTs with increased compression.

 

In your example there are several unstated and uncontrolled variables that could have caused the results you stated - was the ambient air pressure and temperature exactly the same on that run a week later?  Did you have to change ignition timing to stay below the knock limit with the increased CR?  Did you use different fuel to accommodate the increased CR?

 

You don't have to take my word for it - it's pretty well established thermodynamic rules. Here's a link to a paper from Stanford University that covers the subject nicely:  http://rescomp.stanford.edu/~efroeh/papers/RDH_Engine_Performance.pdf

 

 

Going by the point you made above, 10 pounds of boost to the same engine will increase combustion efficiency decrease the amount of gases exhausted as in your example?

 

If not, what makes it different?

 

Some variables are not being considered.

 

I'm just relaying real life observations through experience gained in the field and tony's stirring the pot.

Edited February 18, 2013 by HowlerMonkey

[TimZ]

Going by the point you made above, 10 pounds of boost to the same engine will increase combustion efficiency decrease the amount of gases exhausted as in your example?

 

If not, what makes it different?

 

Some variables are not being considered.

 

What does adding 10-psi boost have to do with this at all?  

[Tony D]

"Ibid"!

[HowlerMonkey]

What does adding 10-psi boost have to do with this at all?  

 

What does adding 1 point of compression have to do with this at all?

 

Your example is missing a lot of data points and it would be necessary to show the configuration of the engine used in your example to even get close to having enough information to prove your point.

 

I relayed real life A vs B comparison with as many variables kept the same as possible.

 

I didn't do one comparison at death valley at 40 degrees and the other at denver at 100 degrees but rather both at sea level at a density altitude of about 18 feet.

 

Tony still has to deliver some sort of proof of all these 1100hp L28s used for endurance racing he mentioned above.

 

 

 

Edited February 18, 2013 by HowlerMonkey

[dexter72]

Howler, Not trying to thread jack

 

Just wanted to ask you a couple of questions, since you performed a piston swap. Then compared the performance numbers.

 

What piston setup did you discover was the better of the two for you?.  What was the timing difference and which setup produced the lower et's?. 

 

Thanks

[TimZ]

What does adding 1 point of compression have to do with this at all?

 

Your example is missing a lot of data points and it would be necessary to show the configuration of the engine used in your example to even get close to having enough information to prove your point.

 

I relayed real life A vs B comparison with as many variables kept the same as possible.

 

I didn't do one comparison at death valley at 40 degrees and the other at denver at 100 degrees but rather both at sea level at a density altitude of about 18 feet.

 

Tony still has to deliver some sort of proof of all these 1100hp L28s used for endurance racing he mentioned above.

 

Well, it was my original point of contention:

 

HowlerMonkey, on 13 Feb 2013 - 10:39, said:

Some of these engines run such a low compression ratio that the engine cannot spool this large turbo when off boost.....regardless of rpm.

...to which I responded:

Sorry, I'm not buying this.  Compression ratio has very little to do with ability to spool.  If anything the lower efficiency of a lower compression ratio means more energy sent unused to the exhaust, which would result in a _faster_ spool.  And I'm dubious as to whether even this effect is measurable.

 

I think I was pretty clear on this point, but then had to elaborate further (see Tony's "Ibid" post).  

 

I pointed out that in your run a week later, we don't know what else changed to cause the engine to stage better.  I pointed out a couple of things (meant as examples, not an exhaustive list) that do have an effect on this that could easily have changed from week to week.

 

It's also entirely possible that the (albeit only ~6%) power increase at the crank from the increased CR would have caused the torque converter to stall at a different RPM, putting you on a different point on the engine's VE curve.  While this would qualify as a secondary effect of the CR increase, it's more of an issue of torque converter selection than being

such a low compression ratio that the engine cannot spool this large turbo when off boost.....regardless of rpm.

 

I don't need any additional data points to show this just like I don't need to do extensive research to show that putting magnets around the fuel lines won't double the fuel economy - it simply doesn't work that way.

 

I'm sorry if this was a thread-jack, but I don't like to see blanket statements made that aren't supported by basic physics.

 

Just to be clear, I'm not saying you are a liar or that your experince didn't happen. But I am saying that your experience in this case does not support the assertion that you made in the above quote.

 

 

 

 

...and btw, that's a much more polite response than you are likely to get from Tony, seeing as how you did just call him a liar.  

Edited February 18, 2013 by TimZ

[Six_Shooter]

I too would like to see more evidence of these 1100 HP L-series of the early '80s. You know a time when making 800 HP from a BBC was very impressive, forced induction or not. I'm not saying that it's impossible, I've just never seen any evidence of it, and have not seen anyone repeat such a feat in more recent years with more available technology and know-how.

[skirkland1980]

If you look on youtube you'll find an SR20 or a 4G63 running in the 6s in the 1/4 mile. I think if you can put 60-80 psi of boost to an engine is just a matter of keeping it together. Oh btw. those are single turbo

Edited February 19, 2013 by skirkland1980

[Xnke]

The evidence you seek can be found in "How To Modify"...

[skirkland1980]

Will this work?

[Tony D]

 

Well, it was my original point of contention:

 

...to which I responded:

 

 

I think I was pretty clear on this point, but then had to elaborate further (see Tony's "Ibid" post).

 

........

 

...and btw, that's a much more polite response than you are likely to get from Tony, seeing as how you did just call him a liar.

Who? What?

I'm Sgt. Schultz here...

Enlighten me what I lied about, I don't see anybody disputing anything I said.

If I missed something, I'll just chalk it up to sour grapes or ignorance on whomever...those two usually cover 99.999% of such claims.

[skirkland1980]

Ok. This thread is about lagging turbos right? Has anyone added pressurized fresh air to the turbine to mix with unburned fuel to spool the turbo? Like the setup in my photo...

[Tony D]

I too would like to see more evidence of these 1100 HP L-series of the early '80s. You know a time when making 800 HP from a BBC was very impressive, forced induction or not. I'm not saying that it's impossible, I've just never seen any evidence of it, and have not seen anyone repeat such a feat in more recent years with more available technology and know-how.

Talk to the boys at Electramotive. Their publicity in Contemporaneous Magazines claims 750HP at 21.6 PSI at 7,500 rpms. When you read (or talk with in person/over the phone) the driver's comments about driving the car (another "Tony" I might add, who had experience in CanAm BBC's BTW...) he stated the Electramotive 280ZXT was the first car he'd ever driven that would/could light the tires at the start of the back straight at Riverside and boil them to the braking point while accelerating the whole way. That doesn't happen with 750HP...

 

Talk with the dyno man, or the builders Knepp & Campbell, they can tell you the engine actually easily ran 9,000RPM's, and routinely ran 30PSI of boost, 7,500 was not even the power PEAK of the engine!

 

These guys are all still around, and they have phones. They appear regularly around at events. As long as you are a credible seeker, and not some time-wasting un credentialed monkey...they WILL talk with you now that the car is not racing competitively. In fact, the reason they shared the knowledge was precisely because some people still compete heads up against full factory sponsored teams, and they felt a kinship with those people (after checking them out thoroughly before sharing, and apparently being satisfied they were not idle Internet time-wasters.) Electramotive was a privateer who received little to no technical assistance from NMC whatsoever. Everything they did technically to the engines was purely their cumulative engineering experience. The direction they steered JeffP & I in was NOT expected. But following their recommendations we have an L28 that makes 735RWHP (SAE Tracability) at 21 PSI, at 7200 RPMS, has NOT reached a power peak in testing, and runs a GT35XR (or whatever that update to the GT35R was acronymed) out of air well before peak power with a camshaft known to be good to peak power at 8,500...

 

So you do the math.

 

If that's not enough in endurance racing....what does a full-bodied 280ZXT weigh, and what horsepower does it take to get a 9.6 0-400 meter time out of it? There were at least three in the "L-Engine Shootout" issue of Carboy, October 1989.

 

To put it bluntly, as I usually do, if you don't know this it's from simple lack of trying! Anybody with credibility can approach these guys and get the straight scoop. As to "why nobody has done this recently" excuse me if I take offence for two people participating in this thread who have duplicated as near as possible, or EXCEEDED those numbers.

 

Like anything on the Internet, you can choose to believe who you want. In this case, keeping you mind closed to those who DO know, and have tried REPEATEDLY to pass on the knowledge results only in the perpetuation of your own ignorance. It's the interwebs, there will always be a few that no matter how hard someone tries to help, they just stick needles and barbs. Better to be an arse, than and ignorant arse I guess. I'm guilty of being an arse. Simply ignore me and you won't have your comfortable paradigm challenged.

 

While Logged in, click the drop down next to your name in the upper right corner of the screen.

Click on "manage ignore prefs"

Put my screen name in there.

 

You will NEVER be bothered by my stupid threads, or any past stupid threads I have ever made. I beseech thee, if it so offends your sensibilities after me having repeated this same information I don't know HOW many times, JUST EFFIN' IGNORE ME and let those who WANT to learn, do so without this repetitive chest-beating "I can't find it, therefore it is highly improbable" B.S. it really does get tiresome after posting the same information repeatedly...

 

For Christ sake, John Coffey has talked to these same people and chimed in on this in the past. Go and do your research!

Edited February 20, 2013 by Tony D

[rayaapp2]

Lord didnt I post this same thread last year... After some research into modern turbos for one of my RB engines I came to the realization 'Complexity' is stupid and abandon my research on compounded turbo setups on gasoline powered engines.

 

I and what got me into that line of thought was the same bit too. BD Twin Bee setup I installed for a customer on his 99 cummins. Works pretty awesome on the Cummins.

 

The post is still in the L series section.

 

In the end the amount of money I would spend on materials and time to make such a setup boiled down to MORE than it would cost for a REALLY nice turbo manifold and a REALLY nice Garrett turbo.

 

Id love to see someone do it still, just because its neat. But I have pots on all the burners and one in each hand so it wont be me.

[Six_Shooter]

735 HP does not equal, nor exceed 1100 HP.

 

Assuming 20% drivetrain loss, that's still only 882 HP, still missing 218 HP.

 

'Hazing tires for an extended period of time' does not equate verifiable numbers.

 

According to my slide rule, it takes about 630 WHP to move 3000 lbs (Curb weight of ZXT is just over 2800 lbs) to the 1/4mile (just slightly longer than than 400 m). Lets round up to 650 WHP, now lets  assume 20% drivetrain loss, that's 780 HP, still quite shy of your supposed 1100 HP.

 

All of these claims seem to be based not on scientifically reproduce-able data, but on seat of the pants, or making assumptions.

 

In the circles I run, I can't use seat of the pants, non-quantifiable stories, to show what has been or can be done. 

 

So there's the math, where does this extra 320 HP come from? That a whole 'nother turbocharged L-series on top.

 

An 800 HP L-series is much more believable, attainable and if memory serves has been near duplicated in street L-series engines in recent years. From everything I have seen, read about and learned about the L-series design, this is about the limit for available air flow, using an L-series head. I haven't seen enough data on "exotic" DOHC, multivalve designed L-series heads, which are either impossible or near impossible to get a hold of, to know if these designs would make enough of a difference to push the power envelope even farther.

 

Getting back to the original topic:

 

Why do you always have to shoot down ideas? I plan to compound charge one of my engines (not an L-series BTW, and because my mind IS open. ), hopefully in the not too distant future (lack of time and money due to school is the hold up right now), even though I could spend more money on a newer turbocharger Garret GT series) that have been shown to spool quickly, and support unheard of power levels for the physical size, but this doesn't men that compound charging is automatically a waste of time, or not something to attempt any longer. 

 

The same argument has been made for single vs twin turbos, yet you still see twin turbos being installed in all forms of vehicles, from OEM to high HP race race cars. but I guess all of these people are doing it wrong too...

 

If someone wants to try something like this, why not give them the information they need to succeed, instead of calling them stupid for trying something a little different?

Edited February 20, 2013 by Six_Shooter

[Six_Shooter]

Lord didnt I post this same thread last year... After some research into modern turbos for one of my RB engines I came to the realization 'Complexity' is stupid and abandon my research on compounded turbo setups on gasoline powered engines.

 

I and what got me into that line of thought was the same bit too. BD Twin Bee setup I installed for a customer on his 99 cummins. Works pretty awesome on the Cummins.

 

The post is still in the L series section.

 

In the end the amount of money I would spend on materials and time to make such a setup boiled down to MORE than it would cost for a REALLY nice turbo manifold and a REALLY nice Garrett turbo.

 

Id love to see someone do it still, just because its neat. But I have pots on all the burners and one in each hand so it wont be me.

 

Do you have a link to the thread? I can't seem to locate it, even searching for threads only started by you.

[rayaapp2]

I just looked and I have no idea where the post is, but I sent a string of pms off to the folks that have real world experience in such things. I invited you to read over the responses in on of those PM's with Tony. Have a read through it.